This invention relates to fluid filters, and more particularly, to the drain assembly for draining contaminants from the collection bowl of such fluid filter.
One of the problems concerned with fluid filter assemblies, particularly for diesel engines and the like, is the removal of contaminants from the filter assembly which typically are collected in the bottom of a collection bowl and which may include not only water removed from the fuel, but solid particulate matter as well. These contaminants can foul the drain valves which are provided in the collection bowl for periodic maintenance purposes, which fouling often affects proper closure of the drain valve or results in the contaminants being retained in the filter assembly for possible reentrance in the fluid being filtered. Another problem associated with devices of this type is the difficulty in removing the contamination from the collection bowl in that if a simple drain valve is employed, a partial vacuum is created in the fluid filter resulting in a difficult, if not impossible, drainage process.
Prior art drain assemblies are known which are self-venting, but these often have been complex and costly to construct. Certain of these devices are constructed in such a manner that portions of the drain assembly might be completely unscrewed and the parts separated with possible loss of a component part. Further, on others there is a risk that the drain assembly might accidentally be left in its open position, with consequent loss of fuel. In many of these devices contamination near the drain or vent valve openings within the collection chamber, may tend to collect and prevent proper closing of the particular drain or vent valve and it would be advantageous to have a valve structure which would tend to clear the upper drain and vent passages during the draining cycle.
One form of prior art drain assembly is shown in U.S. Pat. No. 4,314,689. In this device the drain valve includes a plug disposed in the internal passage which cooperates with a transverse bore in the drain valve in such a manner as to prevent contamination of the actuation device. This form of valve provides an efficient type of drain valve which is not so subject to clogging conditions.
Another form of drain valve assembly is shown in U.S. Pat. No. 4,502,956. In this assembly the drain valve is designed to cooperate with first and second collection zones within the collection portion of the filter, which zones are walled off from one another and commonly relieved by the drain valve mechanism. In this arrangement one contaminant outlet is upstream of all of the filter media in the filter assembly and the second contaminant outlet is downstream of at least a portion of the filter media.
Still another form of drain valve assembly is shown in U.S. patent application Ser. No. 784,300 now U.S. Pat. No. 4,724,074 assigned to the assignee of the instant invention. This drain assembly has a self-venting feature wherein a first opening in the valve assembly is uncovered to allow an initial discharge of the fluid in the collection bowl or the like, with a second opening thereafter uncovered to allow air to be introduced into the collection bowl to assist in the drainage process. This form of drain valve assembly comprises a threaded plug having plural passages therein and which are in fluid communication with a pair of outlets in the bottom wall of the collection bowl, one of the outlets being at a higher elevation therein than the other.